Recently, various kinds of healthcare support systems for women useful for promotion of pregnancy and contraception, basal body temperature measurement systems using a mobile information terminal such as a mobile phone, menstrual cycle estimation programs used for a woman to estimate her menstrual cycle, and the like have been proposed. Such systems will be helpful for a user in promotion of pregnancy, health care management and the like by providing various kinds of information to the user on the basis of data of a menstrual cycle.
Information that can be used as a basis for promotion of pregnancy for women includes menstrual days and an ovulation day. Women's menstrual days and ovulation day are thought to have a regular periodicity.
Among the systems proposed so far, however, though there are systems which can estimate whether ovulation occurs or not, there are not systems which can estimate an ovulation day. Actually, a woman cannot know her own ovulation day unless she undergoes an examination.
If an ovulation day can be estimated, accuracy of predicting a next ovulation day can be improved. Furthermore, if an ovulation day can be estimated, it is possible to accurately separate a low temperature period and a high temperature period, and, therefore, it is possible to improve accuracy of determining a hormone balance state from change in basal body temperature.